The present disclosure is directed toward methods and systems for providing structural reinforcement.
Many products have bodies or housings with hollow cavities therein. For example, various consumer appliances and vehicles may have hollow cavities formed between inner and outer panels of the bodies or housings, such as in pillars or within frame members. In particular, some structural members of automobile bodies include a variety of pillars, members, rails, beams, posts, etc. (collectively referred to as “cavities”) connected by one or more nodes. Such hollow pillars, beams, etc., often assist in reducing the overall weight of the final product, as well as reducing material costs. However, these cavities often result in a structural member that lacks sufficient strength or energy-absorbing characteristics.
One way to compensate for a weakened structural member is to provide a structural reinforcer within the cavity of the member. Structural reinforcers often include a carrier with an expandable material configured to expand and mold to an inner surface of the structural member. The carrier portion is typically a molded component made from nylon, glass-reinforced nylon, metal, or some combination thereof, and is designed to be lightweight yet stiff. The carrier may also include a plurality of ribs configured to increase the carrier's response to specific stresses.
While effective, the molded carrier structural reinforcers described above have drawbacks. For instance, expandable foam layers generally are relatively large, and provide only moderate strength increases, particularly with regard to shear and tensile stresses. The portions of the reinforcer which are foamable material lack the comparable strength of the molded carrier portion. Further, in order to achieve sufficient expansion of the foam, such reinforcers generally require a large gap between the carrier and an interior wall of a cavity to be reinforced. The required gap between the molded carrier and the interior walls defining the cavity is generally a minimum of 6-10 mm. With a gap of this size, it is possible that the gap will not be properly sealed when the foam expands, due to conditions such as high assembly tolerances, variations in baking conditions, etc. If, for example, the foam does not expand uniformly, it is possible that portions of the gap will remain unsealed, or that the carrier will not be properly secured within the cavity. Further, it is difficult to design a foaming structural reinforcer including one or more channels within the cavity, to allow fluid, such as e-coat fluid, to flow therethrough. Additionally, expandable foam reinforcers generally provide only moderate reinforcement with regard to shear and tensile loads.
Other reinforcers have been designed using an injectable adhesive that flows between the reinforcer and the structural member, to adhere the reinforcer thereto. Using an injectable adhesive allows portions of the gap between a carrier and one or more inner walls of the cavity to be reduced, as it is not necessary to provide room for expansion of the expandable foam across the entire carrier. However, methods including injectable adhesives also have drawbacks. Current methods using injectable adhesives generally require introduction of a sealing material between the carrier and one or more inner walls of the cavity, to prevent the injectable adhesive from flowing out of the cavity. The sealing material generally consists of an expandable foam or mastic. This process thus involves additional steps, and additional materials, including the application of sealing material, and the curing of sealing material, in addition to the subsequent injection and curing of the adhesive material. This requires additional time and expense to create a reinforced part. This also necessitates that timing be more closely controlled, as adhesive generally cannot be injected until the sealing material is at least partially cured. Further, injecting adhesive into a cavity generally fills the entire gap with adhesive, making it difficult to provide channels for e-coat flow.